Robinson has a minor knee injury and Butler apparently tore his anterior cruciate ligament in a collision with running back Mark Ingram during one of the team’s final organized team activities in June.

Butler, one of the team’s top pickups in free agency this spring and the projected starter at strongside linebacker, will likely be sidelined for the entire season.

Harper’s injury is unknown.

Saints sign safety

The Saints signed safety Akwasi Owusu-Ansah, a two-year NFL veteran, to a one-year contract and waived cornerback Ryan Steed on Tuesday.

A fourth-round draft pick of the Dallas Cowboys in 2010, Owusu-Ansah appeared in 14 career games with two starts with the Cowboys and Jacksonville Jaguars in 2011.

Owusu-Ansah, who has played in the secondary and wide receiver, also returned punts and kickoffs. The 6-foot-1, 207-pounder went to training camp with the Cowboys last summer and then spent most of the season on the Oakland Raiders practice squad.